The San Antonio Spurs are operating under the premise that Tim Duncan will return in 2015-16 for a 19th NBA season, according to league sources.

Although Duncan and fellow Spurs mainstay Manu Ginobili have yet to make formal declarations about their plans for next season, sources said that the Spurs are optimistic about re-signing both at salaries that will allow the team to re-sign prized restricted free agent Kawhi Leonard this summer and to pursue top-tier free agent LaMarcus Aldridge.

It has been widely assumed in league circles that the Spurs would be forced to try to trade veteran forward Tiago Splitter to help create the needed salary-cap flexibility to handle the max deals San Antonio has earmarked for Leonard (and the likes of Aldridge or Memphis’ Marc Gasol) and still have room to accommodate Duncan and Ginobili at reduced salaries, if the latter two choose to play on. But sources told ESPN.com that the Spurs actually rebuffed trade interest from teams hoping to pry Splitter away in conjunction with Thursday’s NBA draft, raising the possibility that Splitter might stick around.